1) Field of Invention
The present invention relates generally to agricultural tillage tools, and, more specifically, to an improved sweep for deep tillage applications.
2) Related Art
Earthworking tools such as deep tillage and ripper shanks have for the most part used a straight, flat point to lift and shatter soil at depths of 10 inches (0.25 meters) or more. Straight points provide a limited shatter zone, and in recent years there has been an increasing desire by many farmers to create a wider shatter zone.
Winged points, such as the commercially available DMI Tiger-Point which is generally of the type shown and described in U.S. Pat. No. 4,538,689, include wings that slope downwardly and outwardly to create an energy demanding boiling effect by pushing soil forwardly and upwardly. Such action often brings up subsoil and leaves large clods on the surface so that additional tillage steps are required to break the clods into smaller pieces for a level surface which is necessary, for example, to provide a suitable seed bed for planting. The inclined wings produce some bulldozing effect and cause the resultant draft angle to be flatter (that is, closer to parallel with the ground) so that more horizontal force and therefore more tractor horsepower is required to move the tool through the ground. In addition, the flatter draft angle increases the moment arm tending to trip the standard, and a larger force is required to keep the shank in the ground. The increased moment requires heavier springs or links to maintain the working position of the standard. As the point wears and becomes blunt, further increase in the draft loads is experienced.
Another disadvantage of some winged point tools is the relatively large distance between the point and the wings which causes the resultant force on the tool to be offset from the resultant force of a straight point for which the standard was designed. Also, the wider tillage zone for the winged point does not start at the lower tip of the point, but is as much as several inches higher than the tip to avoid a plow sole. The large vertical offset between the point and the wings results in an inconsistent depth of tillage.
Recently, tests of draft angle on various tools has shown that the resultant draft angle on a conventional sweep is very similar to the straight, flat point. However, conventional sweeps are unacceptable for deep tillage and ripper shank applications at depths of 10 inches or more because the sweep wears too quickly.